Time Machine extremely slow on Mountain Lion remote host

Discussion in 'OS X Mountain Lion (10.8)' started by aubryric, Aug 13, 2012.

  1. aubryric macrumors newbie

    Aug 13, 2012
    After the switch to Mountain Lion, the backup strategy I used for years no longer works. I have two iMacs at home, each with an external hard drive used for Time Machine backups. Each iMac backup locally to the external hard drive and remotely to the external drive of the other iMac. My network is wired through my router; all the devices use Gigabit Ethernet. Normally one of the external drives is kept out of the house.

    Ten days ago I replaced one of the iMacs with a new one and I immediately installed Mountain Lion on it. After the complete installation of all my stuff on that new Mac, I updated my local backup and I erased the backup on the remote Mac (which was still on Lion) and created a new one; this took normal time, about 3 hours for 215 GB (1.2 GB/min). But when I went to update the backup of the other iMac remotely on the new one, it was very slow. I then erased that backup and began a new one. It was extremely slow (about 11 MB/min) and Time Machine said that it will take 5 days to complete the 65 GB backup (compare to the 3 hours for 215 GB above).

    I thought that this could be caused by a bad interaction between Lion and its successor. So I upgraded the other iMac to Mountain Lion. After that, same problem: the local backup went normally but the remote backup was still very slow. And now the remote backup from my first iMac is also extremely slow on the Mountain Lion host. I erased that backup and tried to create a new one; this time it didn’t complete in 3 hours but Time Machine estimated that the 215 GB will be backed up in 15 days!

    After that, I also tested the direct copy from a Mac to the other and concluded that all is normal on that side. The copy of a 2 GB folder containing 82 files took about 35 seconds.

    So, my experience shows that
    1. backing up from either Lion or Mountain Lion to a remote host that is NOT under Mountain Lion goes normally;
    2. backing up from either Lion or Mountain Lion to a remote host that is under Mountain Lion is abnormally slow.

    Do you share similar experience? Have you found some solution?

    Hope Apple will address that issue real soon now!
  2. robgendreau macrumors 68040

    Jul 13, 2008
    Have you considered spotlight indexing? Is it turned on on the externals?
  3. aubryric thread starter macrumors newbie

    Aug 13, 2012
    I didn't exclude the external drives in Lion nor in Mountain Lion. In the Help Center, it is said that it's impossible to exclude from indexation a drive used for Time Machine backup: even if it is on the excluded list, indexation will occur if it is used for Time Machine.
  4. olkhovp macrumors newbie

    Mar 6, 2008
    Time Machine copy to 2.0 external drive VERY SLOW

    I am using a 2010 iMac and tried a completely new 250+Gb Time Machine copy to a WD Passport 2.0 500Gb external HD. It's taking something like more than 2 days. Never took that long before. Not a web or wi-fi issue. Before Mountain Lion, should have taken 3-4 hours max. Any ideas?
  5. Steveorevo macrumors newbie

    Jul 27, 2010
  6. olkhovp macrumors newbie

    Mar 6, 2008
    Thanks to dolfke in Apple Support Communities Blog, running "sudo tmdiagnose" in the terninal really worked. I couldn't tell you why, but my TM backup time increased by 10X's.

    For ref:


    Re: time machine very slow with mountain lion

    Aug 19, 2012 6:25 AM (in response to 1tombhome)

    How to run tmdiagnose

    1) Launch Terminal.app (/Applications/Utilities/Terminal.app)
    2) Enter the command text below followed by the Return key on the Terminal command line:

    sudo tmdiagnose

    3) Enter your admin password when prompted and wait for all of the tmdiagnose processes to finish.
  7. Enjay314, Oct 2, 2012
    Last edited: Oct 3, 2012

    Enjay314 macrumors newbie

    Oct 2, 2012
    Thanks olkhovp and dolfke!


    @olkhovp/@dolfke's solution above worked for me at first to get my 400 day backup estimate down to mere hours... (I am going from Lion to Snow Leo, over network)

    But this solution, summed up here, got it down to under an hour (for 20GB)

    I rebooted after running each Spotlight command... but apparently the key is unload Spotlight at boot, run the Time Machine, and then you can reload Spotlight at boot.... Time Machine will work fine after that.

  8. Hanas macrumors newbie

    Jul 29, 2011
    Thanks but ... problem remains

    Thank you all for ideas and suggestions, but, neither solution seems to be working for me (Mountain Lion 10.8.2, MacBook Pro). Still many, many hours of backing up time, much more than under Lion, no matter what I do whith Spotlight or diagnose ...

    Any more ideas ??
  9. rhoydotp macrumors 6502


    Sep 28, 2006
    what's the current throughput on the disks (both local & remote)?
  10. elistan macrumors 6502a

    Jun 30, 2007
    Denver/Boulder, CO
    As silly as it sounds, sometimes trying something you've already tried, works. So: Delete the existing TimeMachine backup file and start over fresh with an entirely new TM backup, even though you already did this once before.
  11. dooly macrumors newbie

    Mar 10, 2013
    Check Ethernet Cabling

    Had the same problem with slooooooow TM backups via Server.app running on a Mac Mini Server. The only thing that worked was getting Cat6 cables and eliminating an old Ethernet hub. Now the server and clients are purring along at 1GBit/s and TM backups are back to anticipated speeds. (Hours instead of days for initial backup and a few hours instead of a dozen hours for incremental backups.)

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